Lea Michele vs. Naya Rivera

"They talk behind each other's backs — a lot," an insider told Us of the Glee costars in April 2014, shortly before multiple sources confirmed Rivera was fired from the FOX series. Though Michele reportedly had little to do with Rivera's exit, separate sources tell Us the girls aren't friendly. "They're always icy to each other. Naya is jealous that Lea is the show's main star . . . There is a lot of sighing and eye-rolling between them."